Handling Json in .Net Core C#

Purpose
This purpose of this brief tutorial is to show how to parse form submission data, when you need to do it manually such as when there are no pre-existing models for a form where you could usually use [FromBody] for .Net to automatically map the data to the model class. This example also shows how to use a List of List.

Ready? Here we go!

/* Form Data name/value Model */
public class FormGenericModel {
	public string ElementName { get; set; } = string.Empty;
	public string ElementValue { get; set; } = string.Empty;
}


using System.Collections.Generic;
using System.Text.Json;
using System.Text.RegularExpressions;
/* Handles an array of objects [{"a":"b"},{...}] */
public List<List<FormGenericModel>> extractArrayJsonPairs(string json) {
	List<List<FormGenericModel>> configData = new List<List<FormGenericModel>>();
	using (JsonDocument jdoc = JsonDocument.Parse(json)) {
		foreach (JsonElement je in jdoc.RootElement.EnumerateArray()) {
			List<FormGenericModel> formData = new List<FormGenericModel>();
			formData = extractJsonPairsOfRegEx(je.ToString());
			configData.Add(formData);
		}
	}
	return configData;
}

/* Handles an object that is not in an array, such as a submitted form {"a":"b", "c":"d"...} */
public List<FormGenericModel> extractJsonPairs(string json) {
	List<FormGenericModel> formData = new List<FormGenericModel>();
	using (JsonDocument jdoc = JsonDocument.Parse(json)) {
		foreach (JsonProperty kv in jdoc.RootElement.EnumerateObject()) {
			var key = kv.Name.ToString();
			var value = kv.Value.ToString();
			formData.Add(new FormGenericModel() { ElementName = key, ElementValue = value });
		}
	}
	return formData;
}

/* Similiar to extractJsonPairs() but decodes regex data in json, such as may be present in a database; turning "%5E%58a-zA-Z0-9%5D*%24" into "^[a-zA-Z0-9]*$" */
public List<FormGenericModel> extractJsonPairsOfRegEx(string json) {
	List<FormGenericModel> formData = new List<FormGenericModel>();
	using (JsonDocument jdoc = JsonDocument.Parse(json)) {
		foreach (JsonProperty kv in jdoc.RootElement.EnumerateObject()) {
			var key = kv.Name.ToString();
			var value = kv.Value.ToString();
			if (value.Trim().Length > 0 && value.IndexOf("%") > -1) { value = Uri.UnescapeDataString(value); }
			formData.Add(new FormGenericModel() { ElementName = key, ElementValue = value });
		}
	}
	return formData;
}